As Ralph says above, this is an undocumented internal API and likely to change, but I had to do this for a client and this code works in 6.x and appears to still work in 7.x but I need to more thoroughly test in the later releases.

This code is used to create a child review task on a work item at a certain point in the workflow, and assign a SME and due date, so it shows creating the item, setting various built in and custom attributes, and creating parent/child link.

Because of the callbacks, it's a bit difficult to read but basically a proxy is created for a new work item, then the settings and values for the content are set up in a params object, including code that sets the values and saves the work item if it's successfully initialised. Finally the initialise is called with the params to kick off the whole create and save:

  var WorkItemAttributes = com.ibm.team.workitem.api.common.WorkItemAttributes;
  var WorkItemProxyFactory = com.ibm.team.workitem.web.cache.internal.WorkItemProxyFactory;

  var valueObject = function(workItem, attr, val) {
    var vo = {
      attributeId : attr,
      path : [ 'attributes', attr, workItem._getIdSegment(attr) ],
      value : val
    };
    return vo;
  };

  var addReview = function(workItem, category, owner) {
    console.log('addReview');
    var newProxy = WorkItemProxyFactory.getWorkItemProxy({
      id : -1,
      createIfNeeded : true,
      doNotGetFromCache : true,
      doNotCache : true
    });

    var params = {

      newWorkItem : true,

      type : "review",
      fetchEditorPresentation : false,
      fetchInlinePresentation : false,
      projectAreaItemId : workItem.getValue(WorkItemAttributes.PROJECT_AREA),
      onSuccess : function() {
        console.log('WI Initialisation Success');
        newProxy.setValue(valueObject(workItem, WorkItemAttributes.SUMMARY, category.name + ': '
                + workItem.getValue(WorkItemAttributes.SUMMARY)));
        newProxy.setValue(valueObject(workItem, 'cpfSummary', workItem.getValue(WorkItemAttributes.SUMMARY)));
        newProxy.setValue(valueObject(workItem, WorkItemAttributes.OWNER, owner));
        newProxy.setValue(valueObject(workItem, WorkItemAttributes.FILED_AGAINST, category.id));
        var dueDate = workItem.getValue(WorkItemAttributes.DUE_DATE);
        if (dueDate === null) {
          dueDate = new Date();
          dueDate = dueDate.setDate(dueDate.getDate() + 2);
        }
        newProxy.setValue(valueObject(workItem, WorkItemAttributes.DUE_DATE, dueDate));

        var linkparam = {
          isNew : true,
          addLinkType : "com.ibm.team.workitem.linktype.parentworkitem",
          addLinkIsSource : "false",
          addLinkedProjectAreaItemId : workItem.getValue(WorkItemAttributes.PROJECT_AREA),
          addLinkedItemId : workItem.getWorkItemItemId()
        };
        newProxy.addLinkTarget(linkparam);

        var saveparam = {
          self : this,
          operationMsg : "Saving",
          applyDelta : true,
          onSuccess : function(param) {
            console.log('WI Save Success');
          },

          onError : function(err) {
            console.log('WI Save Error');

            console.log(err);

          }

        };
        newProxy.storeWorkItem(saveparam);
      },
      onError : function(err) {
        console.log('WI Initialise Error');
        console.log(err);
      }
    };
    newProxy.initialize(params);
  };

The valueObject function simply converts an attribute or link into the required internal format the work item uses during storage - it's a Java script object that consists of the attribute name, value and its 'path' which is the internal hierarchy its stored under.

The _getIdSegment() function returns this path.

As mentioned before, this snippet was created to create a SME Review child work item at a particular point in the overall workflow of the parent. The SME review data was derived completely from the parent's content so you're correct, but you could use any data you like, passed in any way you like. In this example:

newProxy.setValue(valueObject(workItem, WorkItemAttributes.SUMMARY, category.name + ': ' + workItem.getValue(WorkItemAttributes.SUMMARY)));

sets the Review's Summary to a string made up of the review category (category is externally derived - it's an object, so this is one example of passing in your own data) plus the parent's Summary attribute

newProxy.setValue(valueObject(workItem, 'cpfSummary', workItem.getValue(WorkItemAttributes.SUMMARY)));

sets a custom attribute to the parent's Summary

newProxy.setValue(valueObject(workItem, WorkItemAttributes.OWNER, owner));

sets the Review's Owner attribute to the owner variable, which is passed in

newProxy.setValue(valueObject(workItem, WorkItemAttributes.FILED_AGAINST, category.id));

sets the Filed Against attribute to the category passed in

var dueDate = workItem.getValue(WorkItemAttributes.DUE_DATE);
        if (dueDate === null) {
          dueDate = new Date();
          dueDate = dueDate.setDate(dueDate.getDate() + 2);
        }
        newProxy.setValue(valueObject(workItem, WorkItemAttributes.DUE_DATE, dueDate));

sets the Due Date of the Review to either be the same as the parent work item, or two days from the current date if no due date was set on the parent

var linkparam = {
          isNew : true,
          addLinkType : "com.ibm.team.workitem.linktype.parentworkitem",
          addLinkIsSource : "false",
          addLinkedProjectAreaItemId : workItem.getValue(WorkItemAttributes.PROJECT_AREA),
          addLinkedItemId : workItem.getWorkItemItemId()
        };
        newProxy.addLinkTarget(linkparam);